Rendering Output suddenly not working?
My renders were not appearing in the output folder as my macintosh was not linked to an icloud account. 

Between my successful and failed renders (about 2 weeks) I had deleted my icloud account and created a new one. I periodically received notifications asking me to sign into an icloud account, but since I don't use icloud, I ignored them. Frustrated, I began running virus checks, reinstalled blender and restarting my computer, but it made no difference. Finally, in an attempt to have everything run smoothly, I signed into icloud (after being asked once again). 

In lay terms, it seemed apple wanted to be happy before it would let a nonnative program follow the right paths. 

After signing into icloud, my renders appeared on the output folder. Hope this helps anyone else experiencing a similar problem.